Described herein are methods for making organoaminosilane compounds that may be useful, for example, as chemical precursor for depositing a silicon-containing film. Also described herein are compounds, more specifically organoamines, organoaminosilane, organoaminodisilane, and/or organoaminocarbosilane compounds, that are suitable for use in a variety of industrial applications.
Organoaminosilanes containing the —SiH3 or —SiH2— moieties are desirable precursors for the deposition of silicon-containing films such as, without limitation, silicon oxide and silicon nitride films or doped versions thereof. For example, volatile compounds such as without limitation organoaminosilanes, organoaminodisilanes, and/or organoaminocarbosilanes are important precursors used for the deposition of silicon-containing films in the manufacture of semiconductor devices. One particular embodiment of an organoaminosilane compound is di-iso-propylaminosilane (DIPAS), which has previously been shown to exhibit desirable physical properties for the controlled deposition of such films. Although DIPAS can be prepared by the direct reaction of di-iso-propylamine (DIPA) or lithium-di-iso-propylamide with monochlorosilane (MCS) or monochlorodisilane (MCDS), MCS or MCDS is not an abundant commodity chemical and is therefore subject to limited availability and price instability. Furthermore, synthesis of organoaminosilanes using MCS may produce stoichiometric amounts of amine hydrochloride salts that can be highly absorbent thereby complicating recovery of organoaminosilane products.
The prior art describes some methods for the production of organoaminosilane compounds. Japanese Patent JP49-1106732 describes a method for preparing silylamines by the reaction of an imine and a hydridosilane in the presence of a rhodium (Rh) complex. Exemplary silylamines that were prepared include: PhCH2N(Me)SiEt3, PhCH2N(Me)SiHPh2, PhCH2N(Ph)SiEt3, and PhMeCHN(Ph)SiHEt2 wherein “Ph” means phenyl, “Me” means methyl, and “Et” means ethyl.
U.S. Pat. No. 6,072,085 describes a method for preparing a secondary amine from a reaction mixture comprising an imine, a nucleophilic activator, a silane, and a metal catalyst. The catalyst acts to catalyze the reduction of the imine by a hydrosilylation reaction.
U.S. Pat. No. 6,963,003, which is owned by the assignee of the present application, provides a method for preparing an organoaminosilane compound comprising reacting a stoichiometric excess of at least one amine selected from the group consisting of secondary amines having the formula R1R2NH, primary amines having the formula R2NH2 or combinations thereof with at least one chlorosilane having the formula R3nSiCl4-n, under anhydrous conditions sufficient such that a liquid comprising the aminosilane product and an amine hydrochloride salt is produced wherein R1 and R2 can each independently be a linear, cyclic or branched alkyl group having 1 to 20 carbon atoms; R3 can be a hydrogen atom, an amine group, or a linear, cyclic or branched alkyl group having 1 to 20 carbon atoms; and n is a number ranging from 1 to 3.
U.S. Pat. No. 7,875,556, which is owned by the assignee of the present application, describes a method for making an organoaminosilane by reacting an acid with an arylsilane in the presence of a solvent, adding a secondary amine and tertiary amine, and removing the reaction byproduct using phase separation and the solvent using distillation.
U.S. Publ. No. 2012/0277457, which is owned by the assignee of the present application, describes a method for making an organoaminosilane compound having the following formula:H3SiNR1R2 wherein R1 and R2 are each independently selected from C1-C10 linear, branched or cyclic, saturated or unsaturated, aromatic, heterocyclic, substituted or unsubstituted alkyl groups wherein R1 and R2 are linked to form a cyclic group or wherein R1 and R2 are not linked to form a cyclic group comprising the steps of: reacting a halosilane having the formula HnSiX4-n wherein n is 0, 1, or 2 and X is Cl, Br, or a mixture of Cl and Br, with an amine to provide a slurry comprising a haloaminosilane compound X4-nHn-1SiNR1R2 wherein n is a number selected from 1, 2 and 3; and X is a halogen selected from Cl, Br, or a mixture of Cl and Br; and introducing into the slurry a reducing agent wherein at least a portion of the reducing agent reacts with the haloaminosilane compound and provides an end product mixture comprising the aminosilane compound.
Korean Patent No. 10-1040325 provides a method for preparing an alkylaminosilane which involves reacting a secondary amine and trichloroalkylsilane in an anhydrous atmosphere and in the presence of a solvent to form an alkyl aminochlorosilane intermediate and a metal hydride LiAlH4 is added to the alkyl aminochlorosilane intermediate as a reducing agent to form the alkylaminosilane. The alkylaminosilane is then subjected to a distillation process to separate and purify the alkylaminosilane.
Reference article entitled “Homogeneous Catalytic Hydrosilylation of Pyridines”, L. Hao et al., Angew. Chem., Int. Ed., Vol. 37, 1998, pp. 3126-29 describes the hydrosilylation of pyridines, e.g. RC5H4N (R═H, 3-Me, 4-Me, 3-CO2Et), by PhSiH2Me, Ph2SiH2 and PhSiH3 in the presence of a titanocene complex catalyst such as a [Cp2TiMe2], which provided high yields of 1-silylated tetrahydropyridine derivatives and the intermediate silyltitanocene adduct, Cp2Ti(SiHMePh)(C5H5N) (I).
Reference article entitled “Stoichiometric Hydrosilylation of Nitriles and Catalytic Hydrosilylation of Imines and Ketones Using a μ-Silane Diruthenium Complex”, H. Hashimoto et al., Organometallics, Vol. 22, 2003, pp. 2199-2201 describes a method to synthesize μ-iminosilyl complexes Ru2(CO)4(μ-dppm)(μ-SiToI2)(μ-RCH:NSiToI2) (R=Me, Ph, t-Bu, CH:CH2) in high yields during the stoichiometric reactions of a diruthenium complex having Ru—H—Si interactions, {Ru(CO)2(SiToI2H)}2(μ-dppm)(μ-η2:η2-H2SiToI2), with nitriles RCN.
Reference article entitled “Titanocene-Catalyzed Hydrosilylation of Imines: Experimental and Computational Investigations of the Catalytically Active Species”, H. Gruber-Woelfler et al., Organometallics, Vol. 28, 2009, pp. 2546-2553 described the asymmetrical catalytic hydrosilylation of imines using (R,R)-ethylene-1,2-bis(η5-4,5,6,7-tetrahydro-1-indenyl)titanium (R)-1,1′-binaphth-2-olate (1) and (S,S)-ethylene-1,2-bis(η5-4,5,6,7-tetrahydro-1-indenyl)titanium dichloride (2) as catalyst precursors. After activation with RLi (R=alkyl, aryl) and a silane, these complexes are known catalysts for hydrosilylation reactions.
Reference article “Iridium-Catalyzed Reduction of Secondary Amides to Secondary Amines and Imines by Diethylsilane”, C. Cheng et al., J. Am. Chem. Soc., Vol. 134, 2012, pp. 110304-7, describes the catalytic reduction of secondary amides to imines and secondary amines by using iridium catalysts such as [Ir(COE)2Cl]2 with diethylsilane as reductant.
The prior art synthesis reactions described above suffer from various deficiencies. For example, in the synthesis routes that do not use a catalyst, the synthesis of organoaminosilane require multiple steps using, for example, (a) arylsilane, triflic acid, secondary amine, and tertiary amine, (b) silylhalogen, excess secondary amine, and metal hydride, or (c) silylhalogen, alkali metal amide, and metal hydride. Each of these synthesis routes requires significant cooling to manage highly exothermic reactions and produce significant amounts of salt byproducts that must be subsequently removed by filtration process.
Alternatively, the synthesis reactions described above that do involve catalytic hydrosilylation of imines, are generally used for the synthesis of secondary amines or, alternatively, for highlighting fundamentally unique catalysts. As such, the aforementioned references do not describe a method for the synthesis, isolation, and purification of organoaminosilanes to be used, for example, as precursors for the deposition of silicon-containing films. It should be noted further that there are no description in the above references wherein, silicon-containing sources such as silane (SiH4), disilane (Si2H6), or methylsilane (MeSiH3) gas are used as the Si—H starting material or silicon source material for the catalytic hydrosilylation of imines to form organoaminosilane or organoaminodisilane compounds, such as, for example, di-iso-propylaminosilane (DIPAS), di-iso-propylaminodisilane (DIPADS), and di-iso-propylaminomethylsilane. Furthermore, there is no prior art that teaches the use of complexes of alkaline earth metals such as Ca, Sr, Ba, which are more abundant and less expensive than many transition metals, as catalysts for the hydrosilylation of imines, whether it be for the synthesis of organoaminosilanes, organoaminodisilanes, and organoaminocarbosilanes or the synthesis of organoamines.
Accordingly there is a need to provide a method of making compounds such as, without limitation, organoamines, organoaminosilanes (e.g., DIPAS), organoaminodisilanes (e.g., DIPADS), and organoaminocarbosilanes, using commercially available reagents in relatively high yields via the catalytic hydrosilylation of imines. There is also a need to provide a method of making organoaminosilanes, such as without limitation, DIPAS, by a means that eliminates or facilitates the separation of the product from reaction mixture. There is a need to provide methods of making organoaminosilanes and/or organoamines that reduces the overall production costs by reducing the costs of reagents used and/or reducing agents. There is a need to provide a method of making organoaminosilanes and/or organoamines that eliminates hazards associated with highly exothermic reactions such as those involving triflic acid, metal amide, and metal hydride reagents. There is a need to provide a method of making organoaminosilanes and/or organoamines that avoids using halosilane starting materials, such that there are reduced halide impurities in the purified product in order to avoid potential halides contamination if the compound is used as a precursor for depositing silicon-containing films. There is also a need for synthesis of compounds such as, without limitation, organoamines, organoaminosilanes, organoaminodisilanes, or organoaminocarbosilanes via hydrosilylation of imines using cheaper, more earth abundant metal catalysts compared to the currently widely used precious metal (Ru, Rh, Ir, Pd, and Pt) catalysts.